Exchange Online – Changes on Reply-URL are coming
Microsoft has identified that one of the Reply-URL used by Exchange Online for authentication and authorization is unsafe.
If you work with Exchange and Exchange Online in hybrid mode, you already know that when a mailbox is moved to Exchange Online, the on-premises Exchange redirect/notify the user to access Exchange Online Outlook Web Access URL when using the ‘old’/on-premises OWA URL.
Well, now Exchange Online can do the same for mailboxes still on or moved back on-premises.
